index
B1Formal & Technical
Definition
Meaning
A systematic list or guide, usually alphabetical, of items, topics, or information with references to their location.
A numerical scale, measure, or indicator used to represent trends, comparisons, or financial values (e.g., economic index); a pointer or indicator; in mathematics, a superscript number showing power; in computing, a data structure for fast data retrieval.
Linguistics
Semantic Notes
Primarily a noun, but frequently used as a verb meaning 'to provide or arrange in an index'. The plural form is 'indexes' for lists in books/databases and 'indices' primarily in mathematical, scientific, and financial contexts.
Dialectal Variation
British vs American Usage
Differences
Plural usage varies: 'indices' is more common in BrE for financial/technical contexts, while AmE often uses 'indexes' more broadly. Verb usage is identical.
Connotations
Both varieties treat it as a formal, precise term. The financial 'FTSE 100 Index' is a specifically British context.
Frequency
High frequency in both, with slightly higher technical/financial usage in AmE.
Vocabulary
Collocations
Grammar
Valency Patterns
index [something] (as [something])be indexed to [something][something] serves as an index of [something]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “a sure index of (something) = a reliable sign of something”
Usage
Context Usage
Business
Refers to stock market indices (e.g., S&P 500) and economic indicators used for benchmarking.
Academic
A list of topics at the back of a book; in research, a statistical measure or variable.
Everyday
The alphabetical list in a book; the forefinger ('index finger').
Technical
In computing, a database index for search efficiency; in mathematics, an exponent or subscript.
Examples
By Part of Speech
verb
British English
- The book has been fully indexed for the new edition.
- Wages are indexed to the rate of inflation.
American English
- The software automatically indexes all new files.
- The bond's return is indexed to the consumer price index.
adverb
British English
- (No standard adverbial form. 'Index-wise' is non-standard and rare.)
American English
- (No standard adverbial form.)
adjective
British English
- Index-linked pensions provide some security.
- He suffered an index finger injury.
American English
- She invests in low-cost index funds.
- The index case of the disease was identified.
Examples
By CEFR Level
- Use the index to find the page about tigers.
- He pointed with his index finger.
- The book's index is very thorough and helpful.
- The Dow Jones Index fell by two percent today.
- Economists use the consumer price index to measure inflation.
- All articles in the database are indexed by keyword.
- The study used body mass index as a primary health indicator.
- The algorithm creates a hash index to optimize query performance.
Learning
Memory Aids
Mnemonic
Think of your INDEX finger – you use it to point to things. An INDEX points you to information.
Conceptual Metaphor
ORDER IS A MAP (An index maps the location of information). MEASUREMENT IS A SCALE (An economic index scales complex data).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'индекс' meaning postal code, which is 'postcode' (UK) or 'ZIP code' (US).
- The mathematical 'index' can be 'показатель степени' (exponent).
- The verb 'to index' is not 'индексировать' in the sense of adjusting salaries for inflation; in that financial context, it's 'привязывать к индексу' or 'индексировать' is acceptable but a calque.
Common Mistakes
- Using 'indices' as the only plural in all contexts.
- Confusing 'index' with 'table of contents' (which lists chapters in order).
- Saying 'look in the index' for a dictionary (it's an alphabetical list of entries, not a separate index).
Practice
Quiz
In which context is the plural 'indices' MOST commonly preferred?
FAQ
Frequently Asked Questions
A table of contents lists chapters/sections in the order they appear. An index lists specific topics, names, and terms alphabetically with page numbers, appearing at the back of the book.
Both are correct plurals. 'Indexes' is often used for book/database lists. 'Indices' is typical in mathematics, science, and economics (e.g., stock market indices). 'Indexes' is becoming more common in all contexts.
Yes. It means to record names/topics in an index (e.g., 'index a book') or to link a value to a standard measure (e.g., 'index wages to inflation').
It is the finger next to the thumb, also called the forefinger or pointer finger. It's called the 'index finger' because it is often used for pointing or indicating.